前言
本打算用CountDownLatch来实现，但有个问题我没有考虑，就是当用户APP没有扫二维码的时候，线程会阻塞5分钟，这反而造成性能的下降。好吧，现在回归传统方式：前端ajax每隔1秒或2秒发一次请求，去查询后端的登录状态。
一、支付宝和微信的实现方式
1.支付宝的实现方式
每隔1秒会发起一次http请求，调用https://securitycore.alipay.com/barcode/barcodeProcessStatus.json?securityId=web%7Cauthcenter_qrcode_login%7C【UUID】&_callback=light.request._callbacks.callback3
如果获取到认证信息，则跳转进入内部系统。
如图所示
2.微信的实现方式
每隔1分钟调用一次 https://login.wx.qq.com/cgi-bin/mmwebwx-bin/login?loginicon=true&uuid=【UUID】&tip=0&r=-1524754438&_=1521943100181
而请求一次的时间预计是1分钟，如果没有查到到认证信息，则会返回
window.code=408;
没有扫码就会一直等待。当一定时间不扫码二维码，页面就会强制刷新。
我猜想后端的机制和我上篇《spring boot高性能实现二维码扫码登录(上)——单服务器版》类似。
那么如果用户长时间不扫二维码，服务器的线程将不会被唤醒，微信是怎么做到高性能的。如果有园友知道，可以给我留言。
3.我的实现方式
好了，我这里选用支付宝的实现方式。因为简单粗暴，还高效。
流程如下：
1.前端发起成二维码的请求，并得到登录UUID
2.后端生成UUID后写入Redis。
3.前端每隔1秒发起一次请求，从Redis中获取认证信息，如果没有认证信息则返回waiting状态，如果查询到认证信息，则将认证信息写入seesion。
二、代码编写
pom.xml引入Redis及Session的依赖：
<!-- redis --><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-redis</artifactId></dependency><!-- session --><dependency><groupId>org.springframework.session</groupId><artifactId>spring-session-data-redis</artifactId></dependency>
完整的pom.xml：
<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.demo</groupId><artifactId>auth</artifactId><version>0.0.1-SNAPSHOT</version><packaging>jar</packaging><name>auth</name><description>二维码登录</description><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.0.0.RELEASE</version><relativePath /> <!-- lookup parent from repository --></parent><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding><java.version>1.8</java.version></properties><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-thymeleaf</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-devtools</artifactId><scope>runtime</scope></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><!-- zxing --><dependency><groupId>com.google.zxing</groupId><artifactId>core</artifactId><version>3.3.0</version></dependency><dependency><groupId>com.google.zxing</groupId><artifactId>javase</artifactId><version>3.3.0</version></dependency><!-- redis --><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-redis</artifactId></dependency><!-- session --><dependency><groupId>org.springframework.session</groupId><artifactId>spring-session-data-redis</artifactId></dependency><dependency><groupId>commons-codec</groupId><artifactId>commons-codec</artifactId></dependency></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin></plugins></build></project>
App.java入口类：
package com.demo.auth;import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication public class App {public static void main(String[] args) {SpringApplication.run(App.class, args);}}
resources/application.properties 中配置使用redis存储session
# session
spring.session.store-type=redis
前端页面index.html和login.html
<!DOCTYPE html> <html xmlns:th="http://www.thymeleaf.org"> <head> <meta charset="UTF-8"> <title>二维码登录</title> </head> <body><h1>二维码登录</h1><h4><a target="_blank" href="http://www.cnblogs.com/GoodHelper/">from刘冬的博客</a></h4><h3 th:text="'登录用户：' + ${user}"></h3><br /><a href="/logout">注销</a> </body> </html>
<!DOCTYPE html> <html xmlns:th="http://www.thymeleaf.org"> <head> <meta charset="UTF-8"> <title>二维码登录</title> <script src="//cdn.bootcss.com/angular.js/1.5.6/angular.min.js"></script> <script type="text/javascript">/*<![CDATA[*/var app = angular.module('app', []);app.controller('MainController', function($rootScope, $scope, $http) {//二维码图片src $scope.src = null;//获取二维码 $scope.getQrCode = function() {$http.get('/login/getQrCode').success(function(data) {if (!data || !data.loginId || !data.image)return;$scope.src = 'data:image/png;base64,' + data.image$scope.getResponse(data.loginId)});}//获取登录响应 $scope.getResponse = function(loginId) {$http.get('/login/getResponse/' + loginId).success(function(data) {if (!data) {setTimeout($scope.getQrCode(), 1000);return;}//一秒后，重新获取登录二维码if (!data.success) {if (data.stats == 'waiting') {//一秒后再次调用 setTimeout(function() {$scope.getResponse(loginId);}, 1000);} else {//重新获取二维码 setTimeout(function() {$scope.getQrCode(loginId);}, 1000);}return;}//登录成功，进去首页 location.href = '/'}).error(function(data, status) {//一秒后，重新获取登录二维码 setTimeout(function() {$scope.getQrCode(loginId);}, 1000);})}
$scope.getQrCode();});/*]]>*/ </script> </head> <body ng-app="app" ng-controller="MainController"><h1>扫码登录</h1><h4><a target="_blank" href="http://www.cnblogs.com/GoodHelper/">from刘冬的博客</a></h4><img ng-show="src" ng-src="{{src}}" /> </body> </html>
bean配置类BeanConfig.java：
package com.demo.auth;import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.data.redis.connection.RedisConnectionFactory; import org.springframework.data.redis.core.StringRedisTemplate;@Configuration public class BeanConfig {@Beanpublic StringRedisTemplate template(RedisConnectionFactory connectionFactory) {return new StringRedisTemplate(connectionFactory);}}
登录处理类：
/*** 登录配置 博客出处：http://www.cnblogs.com/GoodHelper/**/ @Configuration public class WebSecurityConfig implements WebMvcConfigurer {/*** 登录session key*/public final static String SESSION_KEY = "user";@Beanpublic SecurityInterceptor getSecurityInterceptor() {return new SecurityInterceptor();}public void addInterceptors(InterceptorRegistry registry) {InterceptorRegistration addInterceptor = registry.addInterceptor(getSecurityInterceptor());// 排除配置addInterceptor.excludePathPatterns("/error");addInterceptor.excludePathPatterns("/login");addInterceptor.excludePathPatterns("/login/**");// 拦截配置addInterceptor.addPathPatterns("/**");}private class SecurityInterceptor extends HandlerInterceptorAdapter {@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)throws Exception {HttpSession session = request.getSession();if (session.getAttribute(SESSION_KEY) != null)return true;// 跳转登录String url = "/login";response.sendRedirect(url);return false;}} }
MainController类修改为：
package com.demo.auth;import java.awt.image.BufferedImage; import java.io.ByteArrayOutputStream; import java.util.HashMap; import java.util.Hashtable; import java.util.Map; import java.util.UUID; import java.util.concurrent.TimeUnit;import javax.imageio.ImageIO; import javax.servlet.http.HttpSession;import org.apache.commons.codec.binary.Base64; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.data.redis.core.StringRedisTemplate; import org.springframework.data.redis.core.ValueOperations; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.PathVariable; import org.springframework.web.bind.annotation.ResponseBody; import org.springframework.web.bind.annotation.SessionAttribute;import com.google.zxing.BarcodeFormat; import com.google.zxing.EncodeHintType; import com.google.zxing.MultiFormatWriter; import com.google.zxing.common.BitMatrix; import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;/*** 控制器* * @author 刘冬博客http://www.cnblogs.com/GoodHelper**/ @Controller public class MainController {private static final String LOGIN_KEY = "key.value.login.";@Autowiredprivate StringRedisTemplate redisTemplate;@GetMapping({ "/", "index" })public String index(Model model, @SessionAttribute(WebSecurityConfig.SESSION_KEY) String user) {model.addAttribute("user", user);return "index";}@GetMapping("login")public String login() {return "login";}/*** 获取二维码* * @return*/@GetMapping("login/getQrCode")public @ResponseBody Map<String, Object> getQrCode() throws Exception {Map<String, Object> result = new HashMap<>();String loginId = UUID.randomUUID().toString();result.put("loginId", loginId);// app端登录地址String loginUrl = "http://localhost:8080/login/setUser/loginId/";result.put("loginUrl", loginUrl);result.put("image", createQrCode(loginUrl));ValueOperations<String, String> opsForValue = redisTemplate.opsForValue();opsForValue.set(LOGIN_KEY + loginId, loginId, 5, TimeUnit.MINUTES);return result;}/*** app二维码登录地址，这里为了测试才传{user},实际项目中user是通过其他方式传值* * @param loginId* @param user* @return*/@GetMapping("login/setUser/{loginId}/{user}")public @ResponseBody Map<String, Object> setUser(@PathVariable String loginId, @PathVariable String user) {ValueOperations<String, String> opsForValue = redisTemplate.opsForValue();String value = opsForValue.get(LOGIN_KEY + loginId);if (value != null) {opsForValue.set(LOGIN_KEY + loginId, user, 1, TimeUnit.MINUTES);}Map<String, Object> result = new HashMap<>();result.put("loginId", loginId);result.put("user", user);return result;}/*** 等待二维码扫码结果的长连接* * @param loginId* @param session* @return*/@GetMapping("login/getResponse/{loginId}")public @ResponseBody Map<String, Object> getResponse(@PathVariable String loginId, HttpSession session) {Map<String, Object> result = new HashMap<>();result.put("loginId", loginId);ValueOperations<String, String> opsForValue = redisTemplate.opsForValue();String user = opsForValue.get(LOGIN_KEY + loginId);// 长时间不扫码，二维码失效。需重新获二维码if (user == null) {result.put("success", false);result.put("stats", "refresh");return result;}// 登录扫码二维码if (user.equals(loginId)) {result.put("success", false);result.put("stats", "waiting");return result;}// 登录成,认证信息写入session session.setAttribute(WebSecurityConfig.SESSION_KEY, user);result.put("success", true);result.put("stats", "ok");return result;}/*** 生成base64二维码* * @param content* @return* @throws Exception*/private String createQrCode(String content) throws Exception {try (ByteArrayOutputStream out = new ByteArrayOutputStream()) {Hashtable<EncodeHintType, Object> hints = new Hashtable<EncodeHintType, Object>();hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.H);hints.put(EncodeHintType.CHARACTER_SET, "utf-8");hints.put(EncodeHintType.MARGIN, 1);BitMatrix bitMatrix = new MultiFormatWriter().encode(content, BarcodeFormat.QR_CODE, 400, 400, hints);int width = bitMatrix.getWidth();int height = bitMatrix.getHeight();BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);for (int x = 0; x < width; x++) {for (int y = 0; y < height; y++) {image.setRGB(x, y, bitMatrix.get(x, y) ? 0xFF000000 : 0xFFFFFFFF);}}ImageIO.write(image, "JPG", out);return Base64.encodeBase64String(out.toByteArray());}}@GetMapping("/logout")public String logout(HttpSession session) {// 移除session session.removeAttribute(WebSecurityConfig.SESSION_KEY);return "redirect:/login";} }
三、运行效果：
如图所示，效果与上篇一样。
目前我在考虑微信的方式。我打算采用 CountDownLatch await一分钟，然后使用消息订阅+广播唤醒线程的方式来实现此功能。如果有懂原理的朋友可以给我留言。
代码下载
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作者：刘冬.NET 博客地址：http://www.cnblogs.com/GoodHelper/ 欢迎转载，但须保留版权
